Materials testing machine



April 2, 1968 D. c. HOLMES MATERIALS TESTING MACHINE 2 Sheets-Sheet 1 Filed May 26, 1965 ff .3 Vf

ff W i D. c. HOLMES 3,375,709

MATERIALS TESTINQ MACHINE 2 Sheets-Sheet 2 April 2, 1968 Filed May 26, 1965 l I /TN v i l l l l l United States Patent O 3,375,709 MATERIALS TESTING MACHINE Donald C. Holmes, North Weymouth, Mass., assignor to Instron Corporation, Canton, Mass., a corporation of Massachusetts Filed May 26, 1965, Ser. No. 458,864 2 Claims. .(Cl. 73-93) This invention relates to materials testing machines.

It is a primary object of the invention to provide such machines in which a movable crosshead is guided for longitudinal movement lbrut yieldably supported against both transverse and endwise movement. Further objects are to provide for such guidance by means that are simple and sturdy.

The invention features a pair of longitudinal guides mounted in opposed longitudinal portions of a testing machine frame, and a pair of shoes carried by a movable crosshead on each end thereof, each pair of shoes gripping therebetween one of the guides. In preferred embodiments of the invention, each shoe of each pair is Ibeveled to provide a pair of spaced coplan'ar beveled guide surfaces, one shoe of one pair is biased toward its guide by a pair of flat springs, the guides have cylindrical surfaces for engagement by the beveled gruide surfaces, and the beveled guide surfaces are in vertical planes at 45 to the endwise and transverse bisector planes, so that the guides cooperate with the shoes to give predetermined yieldable support against crosshead movement in either a transverse or an endwise direction.

Other objects, advantages, and features will appear from the following description of a preferred embodiment, taken with the attached drawings thereof, in which:

FIG. 1 is an isometric view of a testing machine including a preferred embodiment of the invention;

FIG. 2 is a broken-away vertical sectional view taken through FIG. 1, enlarged;

FIG. 3 is a sectional view taken along line 3 3 of FIG. 2, shown rotated 90;

lFIG. 4 is a side elevation, partially in section, of the shoe construction;

FIG. 5 is an enlarged view, partially in section, of the upper bearing assembly of said embodiment; and

FIG. 6 is an enlarged view, partially in section, of the lower bearing assembly thereof.

.Referring to FIGS. 1 and 2 of the drawings, there is shown a base 10 on which is mounted a pair of opposed vertical channel-shaped columns 12. Fastened in the center of inner wall 14 of each column 12 (only one of which is shown in FIG. 2, all the structure shown in FIG. 2 being in both sides 'of the machine, except that both guide shoes in the unshown side are like shoe 96) is a guide rod 16.

Mounted on the ends of each column 12 are plates 20, 22. Plate 22 is fastened -to the base 10 while plate 20 is fastened to a Xed crosshead 24. The Xed crosshead indicated generally at 24 is made up of four plates 30, 32, 34, 36. In plates and 32 are holes 42 and 44, adapted to receive a load cell (not shown).

An upper bearing assembly 46 is mounted in plate 32 and plate 20. A lower bearing assembly 48 is supported at the lower end of column 12 through plate 22 and base 10. A lead screw 50 is now supported between bearing assemblies 46 and 48.

Mounted on lead screw 50 is the movable crosshead indicated generally 'at 52. The movable crosshead 52 is made up of four plates 54, 56, 58, 60, plates 58 and 60 being slightly longer than plates 54 and 56, for reasons to be described later. In plates 54 and 56 are holes 62, 64,

adapted to receive tensile testing grip apparatus 65. At the ends of movable crosshead 52 and in alignment with lead screw 50 are driving nuts 66 and 68.

Referring now to driving nut 66, there is a flange 72 fastened to plate 54 by cap screws 74. The lower portion 76 of driving nut 66 passes through hole 78 in plate 54.

The driving nut 68 comprises an Unthreaded upper portion 80 and a threaded lower portion 82. The threaded portion 80 is set in flange 57 of plate 56, while the threaded lower portion 82 receives anti-back lash nut 84 and lock nut 86.

Compression spring 88 is centered around driving nuts 66 and 68 and between the lower surface of plate 54 and top surface of upper portion 80 of driving nut 68. The spring 88 biases the nuts against the screw to prevent lost motion (screw rotation without nut movement) on reversals of direction of screw rotation.

At the lower end of lead screw 50 is gear 90, driven by means not shown, to drive movable crosshead 52 up or down.

Referring now to FIGS. 3 and 4, two cap screws 92, 94 are passed through plate 68 and screwed into beveled guide shoe 96, and socket head set screw 98 is screwthreadedly engaged through plate 60 to t in an unthreaded hole in guide shoe 96, and provided with jam nut 100 to prevent slippage.

Two more cap screws 102, 104 are passed through plate 58 and screwed into takeup shoe 97, with adjusting screw 106 threaded into plate 58. Within takeup shoe 97 are loading springs 108, 109.

With the combination of loading spring 108 and adjusting screw 106, the guide shoe 96 and takeup shoe 97 can be fitted snugly on guide rod 16 at Contact surfaces 110, 112, thus arresting the motion of movable crosshead 52 in the transverse and endwise directions.

To adjust guide shoe 96 and takeup shoe 97, the shoes are centered on guide rod 16, and adjusting screw 106 is tightened as muc'h as loading springs 108, 109 allow and then backed off slightly to give the shoes the snug t necessary to prevent horizontal motion without hindering vertical motion.

It will of course be understood by those skilled in the art that various changes may be made in the construction and arrangement of parts without departing from the spirit of the invention as set forth in the following claims.

What is claimed is:

1. In a materials testing machine, the combination which comprises:

a crosshead mounted for vertical movement on a pair of opposed, sidewise-spaced, longitudinally-extending, drive screws with parallel axes;

a pair of longitudinally-extending guides with cylindrical guide surfaces having parallel axes, one of said guides being mounted adjacent and with the aXis of its guide surface parallel to the axes of each of said drive screws;

a pair of shoes positioned between said crosshead and each of said guides,

each shoe including a pair of spaced upper and lower coplanar Vertical guide surfaces defined by planes at an angle to transverse and endwise planes cooperating with one of said guides, said one imposing on said shoe a force having both a sidewise and a transverse component,

each shoe being adjustable in a direction transverse to said crosshead for adjusting said crosshead relative to said guides; and

a pair of at springs yieldably biasing one of said shoes toward its respective guide.

References Cited UNITED STATES PATENTS Lowthorp 73-93 -Daw 308-3 Locas 100-214 Craley 308-3 Bullard 308-3 -Forkner 10G-214 10 Klatchko 73-93 Lindsey 73-103 4 FOREIGN PATENTS 1,055,361 4/1959 Germany.

2,970 11/ 1863 `Great Britain.

OTHER REFERENCES Universal Testing Machines, Cat. 50, part L, Tinius Olsen Testing Machine Company, 1936, pp. 40, 47, 48 and cover.

RICHARD C. QU-EISSER, Primary Examiner.

JAMES GILL, Examiner.

J. H. WILLIAMSON, Assistant Examiner. 

1. IN A MATERIALS TESTING MACHINE, THE COMBINATION WHICH COMPRISES: A CROSSHEAD MOUNTED FOR VERTICAL MOVEMENT ON A PAIR OF OPPOSED, SIDEWISE-SPACED, LONGITUDINALLY-EXTENDING, DRIVE SCREWS WITH PARALLEL AXES; A PAIR OF LONGITUDINALLY-EXTENDING GUIDES WITH CYLINDRICAL GUIDE SURFACES HAVING PARALLEL AXES, ONE OF SAID GUIDE BEING MOUNTED ADJACENT AND WITH THE AXIS OF ITS GUIDE SURFACE PARALLEL TO THE AXES OF EACH OF SAID DRIVE SCREWS; A PAIR OF SHOES POSITIONED BETWEEN SAID CROSSHEAD AND EACH OF SAID GUIDES, EACH SHOE INCLUDING A PAIR OF SPACED UPPER AND LOWER COPLANAR VERTICAL GUIDE SURFACES DEFINED BY PLANES AT AN ANGLE TO TRANSVERSE AND ENDWISE PLANES COOPERATING WITH ONE OF SAID GUIDES, SAID ONE IMPOSING ON SAID SHOE A FORCE HAVING BOTH A SIDEWISE AND A TRANSVERSE COMPONENT, EACH SHOE BEING ADJUSTABLE IN A DIRECTION TRANSVERSE TO SAID CROSSHEAD FOR ADJUSTING SAID CROSSHEAD RELATIVE TO SAID GUIDES; AND A PAIR OF FLAT SPRINGS YIELDABLY BIASING ONE OF SAID SHOES TOWARD ITS RESPECTIVE GUIDE. 